Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 071151
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
450 AM PDT TUE JUL 7 2015

UPDATED AVIATION AND FIRE DISCUSSIONS.

.DISCUSSION...A  CLOSED LOW OFF THE COAST OF CALIFORNIA WILL
SLOWLY PUSH INLAND TOWARDS THE SAN FRANCISCO BAY AREA TODAY,
FINALLY CROSSING ONSHORE WEDNESDAY AFTERNOON AND EVENING. THE
RESULTING FLOW PATTERN IS PUSHING A SUBSTANTIAL AMOUNT OF MOISTURE
INTO OUR REGION. PRECIPITABLE WATER VALUES ARE FORECAST TO REACH
THE TOP 1% TO 10% OF CLIMATOLOGY LATER TODAY AND WEDNESDAY OVER
MUCH OF THE FORECAST AREA. WITH INSTABILITY IN PLACE, AND SHORT
WAVE ENERGY SLIDING OVERHEAD FROM THE SOUTH, NUMEROUS SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON AND EVENING.
WITH SUCH HIGH MOISTURE VALUES, THESE STORMS COULD DROP HEAVY
RAINFALL, WHICH WOULD BE A WELCOME SIGHT IN TERMS OF THE LONG TERM
DRY CONDITIONS SEEN IN SOUTHERN OREGON AND NORTHERN CALIFORNIA.
CONVECTIVE ACTIVITY WILL ONCE AGAIN BE CONCENTRATED FROM THE
CASCADES EAST AND SISKIYOUS SOUTH, BUT SOUTHEAST STEERING FLOW
SHOULD BE ENOUGH TO BRING SOME SHOWERS AND STORMS WEST OF THE
CASCADES, ESPECIALLY SOUTH OF THE UMPQUA DIVIDE TUESDAY EVENING.
FLOW WILL TREND MORE EASTERLY WEDNESDAY, AND ALTHOUGH THUNDERSTORM
CHANCES WILL BE CONCENTRATED SLIGHTLY FURTHER SOUTH, VERY SIMILAR
STORM BEHAVIOR IS EXPECTED, AND CELLS COULD MAKE THEIR WAY ACROSS
THE CASCADES AND INTO SOUTHWESTERN OREGON. MODEL SOLUTIONS DEPICT
INSTABILITY REMAINING OVER THE REGION THROUGH THE OVERNIGHT HOURS,
SO NOCTURNAL THUNDER IS NOT OUT OF THE QUESTION TONIGHT OR
WEDNESDAY NIGHT.

THE LOW WILL BEGIN TO OPEN AND KICK TOWARDS THE NORTHEAST BY
THURSDAY. HOWEVER, MOISTURE AND INSTABILITY WILL REMAIN IN THE AREA,
AND THUNDERSTORMS CHANCES WILL CONTINUE THURSDAY AFTERNOON AND
EVENING. FRIDAY AFTERNOON WILL BE THE LAST HURRAH OF THE DEPARTING
LOW, WITH AFTERNOON AND EVENING THUNDERSTORMS GRADUALLY ENDING FROM
SOUTH TO NORTH AS THE MAIN BELT OF ENERGY EXITS THE REGION.

THIS WILL NOT BE THE LAST OF THE CONVECTION CHANCES OVERALL. THE
SECOND TROUGH WILL BEGIN TO DIG SOUTH JUST OFFSHORE THROUGH
SATURDAY, THEN SLOWLY SLIDE EAST ACROSS THE FORECAST AREA SUNDAY
THROUGH TUESDAY. PRECIPITATION CHANCES WILL CONTINUE THROUGH THIS
TIME, BUT AS MODELS HAVE BEEN INCONSISTENT DURING THIS TIME FRAME,
CONFIDENCE IS LOW CONCERNING ANY DETAILS IN TIMING OR PLACEMENT.
HAVE THEREFORE KEPT SLIGHT CHANCE POPS IN PLACE THROUGH MUCH OF THE
EXTENDED TERM.

THE MOST NOTICEABLE CHANGE RESULTING FORM THIS PATTERN WILL BE THE
SOMEWHAT DRASTIC DROP IN TEMPERATURES FROM THE EXCEEDINGLY HOT
CONDITIONS SEEN OVER THE PAST FEW WEEKS. HIGH TEMPERATURES TODAY ARE
EXPECTED TO BE AROUND 5 TO 10 DEGREES ABOVE SEASONAL NORMALS, BUT BY
THIS WEEKEND AND INTO EARLY NEXT WEEK, WE WILL LIKELY SEE DAYTIME
HIGHS OF 5 TO 10 DEGREES BELOW NORMAL. WITH AMPLE CLOUD COVER
OVERHEAD, HOWEVER, NIGHTTIME LOWS SHOULD REMAIN AT OR NEAR VALUES
NORMAL FOR THIS TIME OF YEAR. -BPN


&&

.AVIATION...FOR THE 07/12Z TAF CYCLE...ALONG THE COAST...MVFR
CEILINGS WITH ISOLATED IFR CIGS IS EXPECTED THROUGH EARLY THIS
MORNING...THEN LOW CIGS ARE EXPECTED TO LIFT TO VFR WITH ISOLATED
MVFR LATE THIS MORNING AS A DISTURBANCE MOVES UP FROM THE SOUTH. LOW
CIGS WITH IFR/MFR CIGS WILL RETURN TO THE COAST THIS EVENING BETWEEN
02-05Z.

AWAY FROM THE COAST...GENERALLY VFR CONDITIONS ARE EXPECTED WITH
SOME ISOLATED SHOWERS POSSIBLE THIS MORNING, MAINLY IN NORTHERN
CALIFORNIA, BUT CIGS SHOULD REMAIN  VFR.  THUNDERSTORM CHANCES WILL
INCREASE THIS  AFTERNOON AND EVENING. SCATTERED STORMS ARE EXPECTED
BY MID TO LATE  AFTERNOON...COVERING MOST OF SOUTHWEST OREGON AND
NORTHERN CALIFORNIA...WITH ISOLATED THUNDERSTORMS POSSIBLE TO THE
COAST SOUTH OF CAPE BLANCO. THESE STORMS MAY BRING ISOLATED MVFR
CIGS AS WELL AS LIMITED VISIBILITIES IN HEAVY DOWNPOURS AND GUSTY
VARIABLE WINDS. /CC

&&

.MARINE...UPDATED 300 AM PDT TUESDAY 7 JULY 2015...WEAK PRESSURE
GRADIENTS WILL PERSIST OVER THE AREA THROUGH THE WEEK. DISTURBANCES
MOVING INTO THE AREA TODAY AND WEDNESDAY, MAY ALLOW SOME ISOLATED
THUNDERSTORMS TO MOVE OVER THE WATERS THIS AFTERNOON THROUGH
WEDNESDAY, MAINLY SOUTH OF CAPE BLANCO. VARIABLE AND LIGHT WINDS
THIS MORNING WILL BECOME LIGHT NORTH TO NORTHWEST THIS
AFTERNOON...INCREASING TO 10 TO 15 KT ON WEDNESDAY. LOW
NORTHWESTERLY SWELL WILL CONTINUE THROUGH THE WEEK WITH SEVERAL
SMALL LONGER PERIOD SOUTH SWELLS MIXED IN...RESULTING IN COMBINED
SEAS OF 4 TO 6 FEET. /CC

&&

.FIRE WEATHER...UPDATED 445 AM PDT TUESDAY 7 JULY 2015...AN UPPER
LEVEL LOW REMAINS OFF THE NORTHERN AND CENTRAL CALIFORNIA COAST
TODAY AND WILL GRADUALLY SHIFT INLAND WEDNESDAY AND THURSDAY.
CONTINUED MOISTURE AND DISTURBANCES MOVING UP FROM THE SOUTH WILL
BRING SCATTERED THUNDERSTORMS TO THE AREA THIS AFTERNOON AND
EVENING. A RED FLAG WARNING HAS BEEN ISSUED FOR SCATTERED
THUNDERSTORMS THIS AFTERNOON AND EVENING. IT WILL COVER MOST OF THE
INLAND AREAS EXCEPT FOR THE LOWER UMPQUA BASIN AND THE EAST SIDE
AREAS THAT HAVE WET FUELS.

SOME OF THE THUNDERSTORMS MAY BE VERY WET. EVEN THE COASTAL AREAS
MAY SEE SOME ISOLATED THUNDERSTORMS TODAY. ADDITIONAL SCATTERED
SHOWERS AND THUNDERSTORMS ARE EXPECTED WEDNESDAY AND THURSDAY. A MIX
OF SHOWERS AND THUNDERSTORMS WILL CONTINUE THIS WEEKEND. THEN EXPECT
SHOWER AND THUNDERSTORM CHANCES TO DIMINISH EARLY NEXT WEEK.

TEMPERATURES WILL START TO COOL TODAY AND WILL APPROACH SEASONAL
VALUES BY FRIDAY. /CC


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING FROM 2 PM THIS AFTERNOON TO 11 PM PDT THIS
     EVENING FOR ORZ616-617-619>624.

CA...RED FLAG WARNING FROM 2 PM THIS AFTERNOON TO 11 PM PDT THIS
     EVENING FOR CAZ280-281-284.

PACIFIC COASTAL WATERS...NONE.

$$

BPN/CC



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